Multicast content distribution networks operate under network group management protocols such as that described by B. Cain et al., Internet Group Management Protocol, version 3, IETF RFC 3376 (October 2002) (hereinafter IGMPv3 protocol). Under that protocol, IP hosts and routers report their multicast group memberships to neighboring multicast routers. The protocol provides for multicast routers collecting membership information, as well as for group members informing multicast routers of their memberships.
The IGMPv3 protocol provides a service interface used by upper-layer protocols or applications to cause the IP layer to enable and disable the reception of packets sent to specific IP multicast addresses. The protocol includes a command to cause a particular multicast address on a specified interface and socket to “listen” to a particular multicast. The IGMPv3 protocol includes parameters for specifying a filter mode for a source list for use at that multicast address.